NIRL-10 LEPTOMENINGEAL ENHANCEMENT WITH PARANEOPLASTIC CEREBELLAR DEGENERATION: AUTOIMMUNE OR METASTASES?

Enhancement has been occasionally reported in patients with paraneoplastic cerebellar degeneration but metastases can also occur in these patients and standard imaging and cerebrospinal cytology lack sensitivity and specificity. Among a retrospective case series of 31 patients with paraneoplastic cerebellar degeneration, 4 patients had enhancement at some point of their MRI. We report a series of four patients with paraneoplastic cerebellar degeneration with enhancement and possible concurrent or subsequent leptomeningeal metastases and review the literature. Patient 1 was a 66 year old man with merkel cell carcinoma who had subacute onset of ataxia with nausea. Initial MRI showed non enhancement cerebellar FLAIR changes. Paraneoplastic panel was negative in blood and CSF and seronegative PCD was diagnosed without response to immunosuppression. Eight months later he developed progressive cerebellar symptoms and diffuse leptomeningeal enhancement was found in the cerebellum and spine consistent with leptomeningeal metastates. Patient 2 is a 50 year old woman with HER2+ breast cancer who developed acute cerebellar symptoms with focal cerebellar enhancement and PCA1 antibody was present. Her symptoms stabilized with immune suppression and enhancement resolved, but CSF showed atypical cells suggestive of concurrent leptomeningeal metastases. Patients 3 and 4 both had serous ovarian carcinoma and subacute onset of cerebellar symptoms with cerebellar enhancement and PCA1 antibody with negative CSF cytology. Both stabilized with immune suppression but within months developed more diffuse widespread CNS nodular enhancement considered to be leptomeningeal enhancement. Enhancement is uncommon but not rare in paraneoplastic cerebellar degeneration, occurring in more than 10% of patients in this retrospective series. Others have reported enhancement in paraneoplastic cerebellar degeneration related to autoimmune process alone, but metastases can also occur and may be difficult to distinguish, creating a diagnostic and therapeutic dilemma.